The influence of sediment correction on the calculation of the effective elastic thickness

Abstract:

The flexural rigidity of the lithosphere is often measured by the effective elastic thickness (Te) which means the resistance to bending under the application of applied, vertical loads. The inverse spectral method for Te calculation, whether continental or oceanic, is often used the relationship between observed gravity (free air gravity anomaly or Bouguer gravity anomaly) and topography data in the spatial frequency (wavenumber) domain, namely the admittance and coherence. Especially in recent years, many authors more and more tend to use the Bouguer gravity anomaly inverting Te by calculating Bouguer admittance and Bouguer coherence. Since the thickness of oceanic sediments is very small compared with the thickness of crust or lithosphere which is several tens of kilometers, few people focus on the influence of the sediment on the Te calculation in oceanic basin. In some studies which areas comprise thick sedimentary basins, we found that the Te is overestimated using the wavelets and Bouguer gravity data in the areas which have thick sediment layers. While the spatial distribution of Te is great changed by using the gravity data after sediment correction under the same method and parameters, such as the overestimates decrease or deviation. So we suggest that the influence of gravity anomalies in sediment layers is very important to the Te calculation in oceanic basins, and it is perhaps better that using the gravity data after sediment correction instead of Bouguer data in inverting Te calculation.